TROCHOCERATID^. 
39 
way between the centre and the convex border ; its elements are 
cylindrical. The surface is ornamented with prominent, rounded 
annulations which are oblique to the long axis of the shell, and 
are as strongly marked upon the cast as upon the test. The annu- 
lations are widest upon the back of the shell, where they form a 
shallow sinus ; they are equally well developed upon the sides and 
upon the concave curvature of the shell. The finer ornaments 
consist of a network of minute lines, of which the longitudinal 
are slightly the stronger. The latter are about | a line distant 
from each other in the centre part of the surface of the shell. 
Of the small (transverse) lines from 6 to 8 may be counted in the 
space of lines. The surface of the cast of the body-chamher 
is covered with epidermids. 
liemarks. The most nearly related species to Trochoceras dis- 
junctum is T. troclioides {ante, p. 35), which is distinguished by its 
more closely contiguous whorls. 
Horizon. Etage E ( = Salopian). 
Localities. Lochkow, Kosorz, Bohemia. 
Well represented in the Collection. 
Trochoceras pulchnim, Barraude. 
18J.8. Trochoceras pulchnim, Barrande, in Ilaidiuger’s Berichte iiber die 
Mittheil. voii Freund, der Naturwiss. in Wien, Band iv. p. 208. 
1807. Trochoceras pulchrum, Barrande, Syst. Sil. de la Boheme, vol. ii. 
pt. i. p. 113, pi. xxviii. ff. 1-8. 
Sp. Char. Shell consisting of two complete whorls, which are 
markedly asymmetrical. The transverse section is elliptical, the 
ratio of the ventro-dorsal to the transverse axis being as 8 ; 7. The 
shell increases its diameter about three times in the course of the 
last volution. The body-chamber, although disconnected from the 
rest of the shell, preserves its curvature ; it occupies about one half 
of the last volution. The aperture has a slight emargination upon 
the convex side. The septa are distant about | the shell-diameter. 
The siphuncle is very small, and is placed close to the centre, but 
towards the convex side ; its elements are cylindrical. The surface 
is ornamented with very oblique acute annulations, which are 
numerous (about 36 in the last volution) and form a deep sinus 
upon the periphery. They become obsolete near the base of the 
body-chamber, and are replaced by lines of growth, the internal 
cast being here quite smooth. Fine transverse lines follow the 
course of the annulations, and they are crossed by less numerous 
longitudinal lines, of which 3 or 4 may be counted in the space of 
